Fig. 5: Multi-scale multi-method characterization of the recent deformation at the Sarpang river site. | Communications Earth & Environment

Fig. 5: Multi-scale multi-method characterization of the recent deformation at the Sarpang river site.

From: Deformed alluvial terraces record an excess of slip over the last few centuries on the Himalayan Topographic Frontal Thrust of central Bhutan

Fig. 5

a Field photograph (see location Fig. 1) shows partially exhumed bedrock (green line is top of Lower Siwaliks) overlain with ca. 2.5-m-thick alluvium from T2. T2 is uplifted by ca. 4 m along the emergence of the Topographic Frontal Thrust (black line)12. Note T2 is incised by ca. 1.5 m for the present stream level. This outcrop was later cleaned and documented in detail for a paleoseimological study by Le Roux‐Mallouf et al.20, who measured a near-horizontal fault dip close to the surface steepening to 27° at the base of the outcrop. b General topography of T0, T2, and T6 terraces at the Sarpang Chu site. Profiles are extracted from the processed photogrammetric DSM (see Methods for details). Field observations (panel a) are reported to scale and correspond to the scarp affecting T2 visible in the profile. The lower insert is the ERT profile (panel c) reported to scale. c Merged multi-scale ERT profile surveyed at the same location. Black inverted triangles indicate the location of electrodes for the three original profiles. Thick black lines indicate the fault’s geometry at depth tested by modeling, i.e., \(\alpha =20^{\circ} -30^{\circ}\) for the shallow section and \(\beta =50^{\circ} -80^{\circ}\) for the deeper section.

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